The present invention relates to a metal laminate gasket having a deformation preventing mechanism, more particularly, a metal laminate gasket having a mechanism to prevent deformation of an elongated portion formed between a gasket edge portion and a hole.
A metal laminate gasket has been widely used to seal between engine parts, such as a cylinder head gasket and a manifold gasket. The metal laminate gasket is formed of a plurality of metal plates laminated together.
A conventional metal laminate gasket used as a cylinder head gasket is shown in FIGS. 1 and 2. The gasket includes a plurality of cylinder bores Hc, water hole Hw (not shown), bolt holes Hb and push rod holes Hp.
In order to provide high power, an engine that the gasket 10 is installed is made as light as possible. Thus, a wall or distance between holes are made as small or thin as possible, such that the push rod holes are made close to an edge of the gasket. Also, the size of the gasket is made substantially the same as in the engine to be completely compressed by the engine parts.
As shown in FIGS. 1 and 2, the push rod hole Hp is made wide to have a length L. Since the push rod hole Hp is located close to the edge of the gasket 10, an elongated portion 11 formed between the push rod hole Hp and the edge of the gasket has a width W less than the length L of the push rod hole Hp.
When the gasket 10 thus formed is installed between a cylinder head CH and a cylinder block CB and is used, the gasket 10 receives pressure due to expansion and contraction of the cylinder block CB and the cylinder head CH. Also, the engine vibrates and pressure at the cylinder head CH changes repeatedly, so that the gasket is compressed repeatedly. As a result, the elongated portion 11 is gradually pushed outwardly as shown in dot lines in FIG. 1.
Especially, in case the gasket is formed of more than three plates, a middle plate is liable to be pushed outwardly. Namely, in case the gasket 10 is formed of an upper plate 12, a middle plate 13 and a lower plate 14, the elongated portion 11' at the middle plate 13 may project outwardly, as shown in FIG. 2. This is because the elongated portion 11' of the middle plate 13 may slide between the upper and lower plates 12, 13 by the repeated vibration of the engine.
In case the elongated portion 11 projects outwardly from the edge of the engine, the sealing at the elongated portion 11 deteriorates. Thus, oil may leak from the push rod hole Hp. If the water hole is formed near the push rod hole Hp, water may leak from the water hole.
In a manifold gasket 15 as shown in FIG. 3, an elongated portions 16 between bolt holes 17 has a width less than a length of a hole 18. Thus, the elongated portions 16 are pushed outwardly when the engine is operated, so that the elongated portions 16 are not sufficiently sealed by flanges of a manifold. Sealing at the manifold gasket may be deteriorated.
Accordingly, one object of the invention is to provide a metal laminate gasket with a deformation preventing mechanism, wherein an elongated portion near an edge of the gasket does not substantially deform when used for a long time.
Another object of the invention is to provide a metal laminate gasket as stated above, wherein sealing near an edge of a gasket is not deteriorated.
A further object of the invention is to provide a metal laminate gasket as stated above, wherein the gasket can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.